1. Field of the Invention
The present invention relates to a television receiver.
2. Description of Related Art
Conventionally, there have been television receivers which output video and audio in compliance with broadcasted signals by receiving the broadcasted signals of a selected channel.
In the television receivers, such a television receiver has been known, which monitors whether or not broadcast signals received via an antenna and a tuner are provided, and simultaneously turns off the power source of the television receiver by judging that the program broadcasting has ended where it is detected that no broadcasting signal is inputted, and where it is detected that a broadcasting signal is a signal associated with a predetermined video pattern (for example, a color bar image or monoscopic image after program broadcasting is ended) (for example, see JP 05-236394A and JP 2001-245238A).
Also, such a television receiver has been known, which monitors availability (presence) of broadcast signals based on a synchronization signal used for channel selection and an AFT signal, and turns off the power source of the television receiver by judging that, where no broadcasting signal is inputted, program broadcasting has ended (for example, see JP 11-203850A).
Further, such a television receiver has been known, which turns off the power source thereof where it is detected that program broadcasting has ended where an invalid video and non-video state are included in video corresponding to inputted broadcast signals and video signals over a predetermined period of time, and where it is detected that an audio-free state is included in audio corresponding to inputted broadcast signals and video signals over a predetermined period of time (for example, JP 09-261554A).
In recent years, such a television receiver has been known, which acquires a chronological fluctuation ratio of image data by comparing the broadcast signals received by the television receiver with the video image data corresponding thereto at predetermined timing since there are cases where a scenery video photographed by a fixed TV camera is continuously broadcasted after predetermined program broadcasting was ended, and judges that the program broadcasting has ended, by judging that, where the fluctuation ratio of the image data is less than a predetermined threshold value, the broadcasting signal is a signal associated with a scenery video after the broadcasting is ended.
However, in cases of such earlier development, there may be cases where, since the fluctuation ratio of image data of the broadcasting signals exceeds a predetermined threshold value by switching display and non-display of weather forecasting at a corner of the scenery video even if the broadcasting signal received by a television receiver is a signal associated with a scenery video after the program broadcasting is ended, it is not possible to judge that the program broadcasting has ended. In such cases, since the power source of the television receiver cannot be turned off although the program broadcasting is ended, there is a problem in that predetermined electric power saving cannot be achieved.
Further, where, when watching a movie on a screen of normal television size (4:3 full screen size), movie images are displayed in the letter box size with a black belt remaining on the top and bottom of the screen so that video images are watched in the wide screen size of 16:9, no video change is provided at the black belt zones, and it is judged that the image fluctuation ratio of image data as the entire video is low, wherein it is judged that the program broadcasting has ended since the fluctuation ratio is made lower than the predetermine threshold value. Therefore, there is another problem in that the power source of the television receiver is turned off while watching a movie.